The 52-year war between the Colombian state and the FARC is the oldest and only armed conflict in the Western Hemisphere, and the last one held over from the Cold War. From Alaska to Tierra del Fuego, war — in the classic sense of a violent conflict over governance or territory fought by at least one national army — has disappeared. Although drug-related gang violence in Latin America continues, the extinguishing of political armed conflicts from an entire hemisphere deserves note.

One has only to look back a few decades to see how momentous a change this is. In Guatemala, El Salvador and Peru, as in Colombia, leftist armed forces battled American-backed governments, with deaths mounting into the hundreds of thousands. In Nicaragua, the conflict was the other way around: American-backed rebels fought to overthrow a leftist government. The United States and the Soviet Union poured in support that kept such wars raging. The “dirty war” in Argentina also flowed from a clash of left and right, in which tens of thousands were killed.

In that era, wars between countries also occurred regularly. During the 1980s, the United States invaded Panama and Grenada to overthrow their governments. In 1982, Britain and Argentina fought a war over the Falkland Islands. Ecuador and Peru skirmished along their contested border, and a simmering dispute between El Salvador and Honduras burst into war in 1969 after the two countries faced off in a series of bitterly contested soccer matches.

The region was also militarized by frequent coups and juntas. In 1981, countries run by authoritarian or military governments included Guatemala, El Salvador, Honduras, Panama, Suriname, Brazil, Bolivia, Paraguay, Chile, Uruguay and Argentina.

Today, there are no military governments in the Americas. No countries are fighting one another. And no governments are battling major insurgencies.

This progress of an entire hemisphere toward peace follows the path of other major regions of the world. Western Europe’s bloody centuries of warfare, culminating in the two world wars, have given way to seven decades of peace. The last military governments in that region, in Greece, Spain and Portugal, yielded to democratic rule in the 1970s. In East Asia, the wars of the mid-20th century — Japan’s conquests, the Chinese civil war and the wars in Korea and Vietnam — took millions of lives. Yet despite serious political disputes, East and Southeast Asia today are almost entirely free from active combat.

In fact, the world’s wars are now concentrated almost exclusively in a zone stretching from Nigeria to Pakistan, an area containing only a sixth of the world’s population. Far from being a “world at war,” as many people believe, we inhabit a world where five out of six people live in regions largely or entirely free of armed conflict.

Latin America can now join that group. Of course, this cannot make us complacent about the horrific violence in the afflicted one-sixth. Rather, by marking the progress in some parts of the world, we can place in sharp focus those parts still ravaged by warfare. Our efforts for peace in those regions can be informed and emboldened by the example of regions like the Americas. War can be transformed from a pervasive means of resolving disputes into something rare, small in scale, and outside the norms of accepted behavior.

Waging peace can be almost as difficult as waging war, and for Colombia, the remaining challenges are considerable. The agreement must be ratified in a plebiscite, and implementing it will require the rebels to surrender their weapons, withdraw from drug trafficking and submit to a procedure of transitional justice. The agreement does not yet embrace a smaller rebel group known as the National Liberation Army, though negotiations are in progress. There must also be investments in rural governance and infrastructure to deal with violence, poverty and corruption.

Post-conflict societies always remain fragile and risk backsliding into war. Only continuing effort, support and vigilance can consolidate and expand the gains that have been made.

Because we have come this far, we know we can go further. Where wars have ended, other forms of bloodshed, such as gang violence, can also be reduced. (In just 25 years, Colombia, for example, has slashed its notoriously high homicide rate by 60 percent.) Since the Americas have succeeded in moving away from war, we know this could happen even in the world’s most stubbornly violent regions.

Progress toward peace moves slowly and uncertainly, but it is propelled by determination, ingenuity and the will of millions — and by the realization that peace is not a utopian ideal but an eminently attainable outcome.

By STEVEN PINKER and JUAN MANUEL SANTOS AUGUST 26, 2016 - THE NEW YORK TIMES

Steven Pinker is a professor of psychology at Harvard and the author of “The Better Angels of Our Nature: Why Violence Has Declined.” Juan Manuel Santos is the president of Colombia.